Patient-specific orthopedic instruments

ABSTRACT

An orthopedic device includes a patient-specific alignment guide operable for preparing a bone of a patient for resection during joint arthroplasty. The alignment guide includes a patient-specific bone engagement surface complementary to a surface of the bone of the patient and imaged from a bone scan of the patient. The alignment guide includes a plurality of guiding bores, and a plurality of alignment pins received through corresponding guiding bores for attaching the alignment guide to the bone. The alignment pins are resorbable and can be cut off during a resection of the bone.

INTRODUCTION

The present teachings provide various patient-specific alignment and resection guides and associated instruments for knee arthroplasty.

SUMMARY

The present teachings provide an orthopedic device that includes a patient-specific alignment guide operable for preparing a bone of a patient for resection during joint arthroplasty. The alignment guide includes a patient-specific bone engagement surface complementary to a surface of the bone of the patient and imaged from a bone scan of the patient. The alignment guide includes a plurality of guiding bores and a plurality of alignment pins received through corresponding guiding bores for attaching the alignment guide to the bone. The alignment pins are resorbable and can be sawn or cut off during a resection of the bone.

The present teachings also provide an orthopedic device that includes a patient-specific tibial alignment guide operable for preparing a tibia of a patient for resection during joint arthroplasty. The tibial alignment guide includes a first portion engageable with a proximal surface of the tibia and a second portion engageable with an anterior surface of the tibia. The first portion defines first and second proximal guiding bores and an opening between the first and second proximal guiding bores. The second portion defines first and second anterior guiding bores and an elongated slot for guiding a blade for resecting the tibia. The tibial alignment guide also includes a patient-specific bone engagement surface defined by the first and second portions and complementary to the proximal and anterior surface of the tibia. The orthopedic device further includes a plurality of alignment pins receivable through respective proximal and anterior guiding bores for attaching the alignment guide to the tibia. The alignment pins are resorbable and can be sawn or cut off during resection of the tibia.

The present teachings also provide a method of preparing a distal femur for a knee joint implant. The method includes mounting a patient-specific bone engagement surface of a femoral alignment guide on a complementary surface of a distal femur a patient. The method also includes inserting first and second resorbable anterior alignment pins into an anterior surface of the distal femur through corresponding first and second anterior guiding bores of the femoral alignment guide, and inserting first and second resorbable distal alignment pins into a distal surface of the distal femur through corresponding first and second distal guiding bores of the femoral alignment guide. The method further includes supporting a distal cutting guide on the first and second anterior alignment pins, passing a cutting blade through a cutting slot of the cutting guide, and resecting the distal femur with the cutting blade by cutting through the alignment guide and the first and second distal alignment pins to form a resected distal surface.

Further areas of applicability of the present teachings will become apparent from the description provided hereinafter. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present teachings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is an environmental perspective view of a patient-specific alignment guide with resorbable alignment pins according to the present teachings;

FIG. 2 is an environmental perspective view of a patient-specific alignment guide with resorbable alignment pins shown cut through during a distal resection according to the present teachings;

FIG. 3 is an environmental perspective view illustrating the cut-off cannulated alignment pins after a distal resection of the femur according to the present teachings;

FIG. 4 is an environmental view of a cutting guide mounted on the cut-off cannulated alignment pins of FIG. 3;

FIG. 4A is a side view of the cutting guide of FIG. 4;

FIG. 5 is an environmental perspective view of a patient-specific alignment guide according to the present teachings;

FIG. 6 is an environmental perspective view of a patient-specific alignment/resection guide according to the present teachings;

FIG. 7 is an environmental perspective view of a patient-specific alignment/resection guide of FIG. 6 shown with a guiding tool;

FIG. 7A is an environmental perspective view a guiding tool according to the present teachings;

FIG. 8A is an environmental perspective view of a patient-specific tibial alignment/resection guide including a tool opening according to the present teachings;

FIG. 8B is an environmental perspective view of a patient-specific alignment/resection guide including a tibial punch opening according to the present teachings;

FIG. 9A is an environmental perspective view of a patient-specific tibial alignment/resection guide including an insert according to the present teachings; and

FIG. 9B is an environmental perspective view of a patient-specific alignment/resection guide including a tibial punch insert according to the present teachings.

DESCRIPTION OF VARIOUS ASPECTS

The following description is merely exemplary in nature and is in no way intended to limit the present teachings, applications, or uses.

The present teachings generally provide various patient-specific alignment and resection guides and other associated instruments for use in orthopedic surgery, such as, for example, in joint replacement or revision surgery. The patient-specific guides can be used either with conventional or patient-specific implant components and can be prepared with computer-assisted image methods. Computer modeling for obtaining three-dimensional (3-D) images of the patient's anatomy using MRI or CT scans of the patient's anatomy, the patient-specific prosthesis components, and the patient-specific guides and templates can be designed using various CAD programs and/or software available, for example, by Materialise USA, Ann Arbor, Mich.

Patient-specific alignment guides and implants are generally configured to match the anatomy of a specific patient. The patient-specific alignment guides are generally formed using computer modeling based on the patient's 3-D anatomic image and have an engagement surface that is made to conformingly contact and match a three-dimensional image of the patient's bone surface (with or without cartilage or other soft tissue) in only one position, by the computer methods discussed above. The patient-specific alignment guides are designed and prepared preoperatively using anatomic landmarks, such as osteophytes, for example, and can be mounted intra-operatively without any registration or other guidance based on their unique patient-specific surface guided by the patient's anatomic landmarks.

The patient-specific alignment guides can include custom-made guiding formations, such as, for example, guiding bores or cannulated guiding posts or cannulated guiding extensions or receptacles that can be used for supporting or guiding other instruments, such as drill guides, reamers, cutters, cutting guides and cutting blocks or for inserting pins or other fasteners according to a surgeon-approved pre-operative plan for performing various resections as indicated for an arthroplasty, joint replacement, resurfacing or other procedure for the specific patient.

The patient-specific guides can also include resection or cutting formations, such as cutting slots or cutting edges or planes guiding a cutting blade to perform bone resections directly through the patient-specific cutting guide. The patient-specific guides can be used in minimally invasive surgery. Various alignment/resection guides and preoperative planning procedures are disclosed in commonly assigned and co-pending U.S. patent application Ser. No. 11/756,057, filed on May 31, 2007; U.S. patent application Ser. No. 12/211,407, filed Sep. 16, 2008; U.S. patent application Ser. No. 11/971,390, filed on Jan. 9, 2008, U.S. patent application Ser. No. 11/363,548, filed on Feb. 27, 2006; and U.S. patent application Ser. No. 12/025,414, filed Feb. 4, 2008. The disclosures of the above applications are incorporated herein by reference.

As disclosed, for example, in the above-referenced U.S. patent application Ser. No. 11/756,057, filed on May 31, 2007, in the preoperative planning stage for a joint replacement or revision procedure, an MRI scan or a series of CT scans of the relevant anatomy of the patient, such as, for example, the entire leg of the joint to be reconstructed, can be performed at a medical facility or doctor's office. The scan data obtained can be sent to a manufacturer. The scan data can be used to construct a three-dimensional image of the joint and provide an initial implant fitting and alignment in a computer file form or other computer representation. The initial implant fitting and alignment can be obtained using an alignment method, such as alignment protocols used by individual surgeons.

The outcome of the initial fitting is an initial surgical plan that can be printed or provided in electronic form with corresponding viewing software. The initial surgical plan can be surgeon-specific, when using surgeon-specific alignment protocols. The initial surgical plan, in a computer/digital file form associated with interactive software, can be sent to the surgeon, or other medical practitioner, for review. The surgeon can incrementally manipulate the position of images of various implant components in an interactive image of the joint. Additionally, the surgeon can select or modify resection planes, types of implants and orientations of implant insertion. After the surgeon modifies and/or approves the surgical plan, the surgeon can send the final, approved plan to the manufacturer.

After the surgical plan is approved by the surgeon, patient-specific alignment/resection guides can be designed using a CAD program or other imaging software, such as the software provided by Materialise, for example, according to the surgical plan. Computer instructions of tool paths for machining the patient-specific alignment guides can be generated and stored in a tool path data file. The tool path can be provided as input to a CNC mill or other automated machining system, and the alignment guides can be machined from polymer, ceramic, metal or other suitable material, and sterilized. The sterilized alignment guides can be shipped to the surgeon or medical facility, for use during the surgical procedure. Various patient-specific knee alignment guides and associated methods are disclosed in the commonly assigned U.S. application Ser. No. 11/756,057, filed on May 31, 2007 (published as 2007/0288030 on Dec. 13, 2007), which is incorporated herein by reference, and are now commercially available from Biomet Manufacturing Corp., Warsaw, Ind. in its Signature™ series.

The various patient-specific alignment guides can be made of any biocompatible material, including, polymer, ceramic, metal or combinations thereof. The patient-specific alignment guides can be disposable and can be combined or used with reusable non patient-specific cutting and guiding components.

Referring to FIG. 1, an exemplary patient-specific femoral alignment guide 100 according to the present teachings is shown mounted on the corresponding patient's distal femur 80. The femoral alignment guide 100 can have a light-weight body 101 with a patient-specific engagement surface 102 that is complementary and made to closely conform and mate with a portion of the anterior-distal surface 84 of the patient's femur 80 based on the pre-operative plan, as described above. The femoral alignment guide 100 can include a window/opening 104 and first and second distal guiding formations 106 defining guiding bores 107 for guiding corresponding distal alignment pins 120. The femoral alignment guide 100 can also include first and second anterior guiding formations 108 defining guiding bores 109 for guiding corresponding anterior alignment pins 122.

In the instruments and surgical techniques used with the patient-specific alignment guides discussed in the commonly assigned and referenced above U.S. application Ser. No. 11/756,057, filed on May 31, 2007, the distal alignment pins may be spring drill pins or other fasteners made of non-resorbable metallic biocompatible materials. Similarly, the anterior pins are metallic trochar pins or other non-resorbable fasteners. After distal and anterior holes are drilled through the bone for the corresponding distal and anterior alignment pins using the alignment guide, the alignment guide is removed. The anterior alignment pins are guided through the anterior holes and a distal cutting block is mounted on the anterior alignment pins to make a distal resection as designed in the pre-operative plan. Similarly, a four-in-one or other cutting block is mounted over the distal alignment pins to make the remaining the resections of the distal femur. Alternatively, the distal alignment pins can be removed and a cutting block having fixed or removable pins attached thereto can be mounted on the femur by placing the pins of the cutting block into separate distal holes prepared using the alignment guide or into the distal holes from which the distal pins were removed. In this manner, the distal and anterior holes and the corresponding distal and anterior alignment pins are reference elements for referencing correctly the placement of the various cutting blocks and the corresponding resections. All the alignment pins are then removed and the prosthetic components are implanted.

In contrast to the above method and according to the present teachings, the distal and anterior alignment pins are made of resorbable materials, such as polymers, and can be sawn or cut off during resection. The portions remaining in the bone can be gradually resorbed, such that the step of removing the alignment pins is eliminated. Referring to FIG. 2, for example, a distal cutting block 200 can be mounted over the anterior alignment pins 122 (only one is visible in the view of FIG. 2), which can pass through corresponding openings 204 of the distal cutting block 200, while the femoral alignment guide 100 is still nested on the distal femur 80. The alignment guide 100 is disposable and made of polymeric material that can also be sawn or cut off. The distal cutting block 200 includes a cutting slot or other cutting guiding formation 202. A cutting blade 230 is guided through the cutting slot 202 and can make the distal resection of the femur 80 sawing through the alignment guide 100 and the resorbable distal alignment pins 120 to create a resected distal surface 82 shown in FIG. 3.

The resorbable distal alignment pins 120 can be cannulated having an inner bore 121 sized for receiving corresponding pins 242 coupled to a 4-in-1 cutting block 240 for making anterior, posterior and chamfer cuts, as shown in FIGS. 3, 4 and 4A. In this respect, the bores 121 reference the location for the cutting block 240. The anterior alignment pins 122 can be also sawn-off or cut-off while making the anterior cut. Alternatively, non-resorbable cannulated distal alignment pins, which are mounted in corresponding pre-drilled holes, can be used for mounting the 4-in-1 cutting block 240 on the resected distal femur 82. In other embodiments, the pins of the 4-in-1 cutting block 240 can be cannulated and slide over non-cannulated distal alignment pins 120. It will be appreciated that when using non-resorbable alignment pins, the alignment pins that are not used to support and guide the cutting block can be removed prior to resection to avoid interference with the resection.

In an alternative embodiment illustrated in FIG. 5, the first and second distal guiding formations 106 of a femoral alignment guide 100′ are positioned obliquely, i.e., not perpendicularly relative to the surface of the medial and lateral condyles, such that the distal alignment pins 120 do not obstruct the distal cut and need not be cut through or removed. The femoral alignment guide 100′ can remain on the distal femur 80 and can be cut through when the distal resection is made, as discussed above in connection with FIG. 2. The distal alignment pins 120 can also be made of resorbable material that can be sawn or cut off.

Referring to FIG. 6, a representative tibial alignment/resection guide 300 is illustrated according to the present teachings. The tibial alignment guide 300 can include a body 301 having a proximal portion 303, an anterior portion 305 and a patient-specific bone engagement surface 302 complementary and made to closely conform and mate with a portion of the anterior surface 72 and proximal surface 74 of the patient's tibia 70 in only one position based on the pre-operative plan. The tibial alignment guide 300 can include first and second proximal guiding formations 306 defining guiding bores 307 for corresponding proximal alignment pins or other fasteners 123. The tibial alignment/resection guide 300 can also include first and second anterior guiding formations 308 defining guiding bores 309 for corresponding anterior alignment pins or other fasteners 127. As discussed above in connection with alignment guides in general and the femoral alignment guide 100 in particular, the tibial alignment guide 300 can be used to drill reference holes for the corresponding proximal and anterior alignment pins 123, 127, which can then be re-inserted as needed for each resection and corresponding resection block after the tibial alignment/resection guide 300 is removed. When using resorbable alignment pins, the alignment pins can remain and be sawn or cut off during resection. In the embodiment illustrated in FIG. 6, the tibial alignment/resection guide 300 can include a resection guiding slot 310 for guiding a tibial resection according to the pre-operative plan for the patient. The tibial alignment/resection guide 300 can be optionally used as a resection guide for resecting the tibia 70 through the guiding slot 310 with a blade or other resection tool while the tibial alignment/resection guide 300 is mounted on the tibia 70.

Referring to FIG. 7, when a tibial alignment/resection guide 300 that is disposable and lightweight is used for making a resection, a metal or other more rigid guide tool 460 can be optionally used by the surgeon for providing additional rigidity and stability for the surgeon while guiding a resection blade 230 (shown in FIG. 2). The guide tool 460 can include an anterior portion 465 having an elongated slot 466, and a proximal portion 463 having first and second apertures 462 that can fit over the proximal guiding formations 306 of the alignment guide 300 and/or the corresponding alignment pins 123, as shown in FIG. 7A. The elongated slot 466 is aligned with the resection guiding slot 310 of the tibial alignment/resection guide 300 when the first and second apertures 462 are aligned over the proximal guiding formations 306. The guide tool 460 can also include a handle 450, which can be integrally or removably coupled to the guide tool 460. Referring to FIG. 7A, the guide tool 460 can also be used over the proximal alignment pins 123, after the tibial alignment/resection guide 300 is removed. Because the proximal alignment pins 123 have been placed through the tibial alignment/resection guide 300, the proximal alignment pins 123 correctly reference the guide tool 460 and the elongated slot 466 of the guide tool 460 for guiding the tibia resection according to the pre-operative plan. A similar guide tool can be configured to be used over the anterior alignment formations 308.

Referring to FIGS. 8A and 8B, tibial alignment/resection guides 350, 370, similar in other respects with the tibial alignment/resection guide 300, can include corresponding proximal openings 352, 372 between the proximal alignment formations 306. The openings 352, 372 can be shaped for guiding various instruments. Referring to FIG. 8B, for example, the proximal opening 372 includes a plurality of fin-shaped slots 371 configured in the shape a punch mask for guiding a finned stem punch through the proximal surface 74 of the tibia 70 along the direction of the intramedullary canal axis in preparation for a tibial stem implant.

Referring to FIGS. 9A and 9B, a tibial alignment/resection guide 390, can include an opening 392 for receiving a removable insert 400 or 425 that is made of a more rigid material, such as, for example, metal or metal alloy. The inserts 400, 425 can be simply placed in the opening or removably coupled by a snap-fit engagement or by a frictional or other mechanical coupling. The inserts 400, 425 can include a corresponding opening 402, 426 shaped for guiding an instrument. The opening 426 of the insert 425, for example, includes a plurality of fin-shaped slots 423 shaped to guide a finned stem punch along the intramedullary canal axis in preparation for a tibial stem implant. Each of the inserts 400, 425 can be used with a modular handle 450 that can be removably coupled with the corresponding insert by a tongue-and groove, dovetail or other coupling arrangement between a distal portion 452 of the handle 450 and a mating portion 404 or 428 of the corresponding insert 400, 425 (details not shown). A plurality of inserts can be provided for selective use by the surgeon in terms of preference or in combination with various punches and corresponding tibial stems.

The various alignment/resection guides described above (100, 100′, 300, 350, 370, 390) can be made of biocompatible polymeric or other plastic materials and are disposable. The alignment/resection guides can be cut through while making various resection cuts. The various alignment pins can be metallic or resorbable. Resorbable pins can be cut off or sawn off or broken off by hand with portions remaining in the bone and resorbed over time. The various alignment/resection guides can also be frangible along score lines or either intentionally weakened portions of the alignment/resection guides. Alternatively, the alignment/resection guides can have modularly coupled portions that can be optionally removed, for example, before performing a resection. Additional details for alignment/resection guides with frangible and/or modularly coupled portions are disclosed in commonly assigned and co-pending patent application Ser. No. 12/571,969, filed Oct. 1, 2009 and published as 2010-0087829 on Apr. 8, 2010, the disclosures of which are incorporated herein by reference.

The foregoing discussion discloses and describes merely exemplary arrangements of the present teachings. Furthermore, the mixing and matching of features, elements and/or functions between various embodiments is expressly contemplated herein, so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise above. Moreover, many modifications may be made to adapt a particular situation or material to the present teachings without departing from the essential scope thereof. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications and variations can be made therein without departing from the spirit and scope of the present teachings as defined in the following claims. 

What is claimed is:
 1. An orthopedic device comprising: a patient-specific alignment guide operable for preparing a bone of a patient for resection during joint arthroplasty, the alignment guide including a patient-specific bone engagement surface configured to be complementary to a surface of the bone of the patient, the alignment guide including a plurality of guiding bores; a plurality of alignment pins receivable through corresponding guiding bores for attaching the alignment guide to the bone, wherein the alignment pins are cannulated, resorbable and configured to be cut off during a resection of the bone; and a cutting block including a plurality of pins configured to be receivable into corresponding cut-off alignment pins for another resection of the bone.
 2. The orthopedic device of claim 1, wherein the alignment guide is configured to be cut off during a resection of the bone.
 3. The orthopedic device of claim 1, wherein the alignment guide is a femoral alignment guide for a distal femur and is configured to be cut off during a distal resection in which a pair of distal pins from the plurality of alignment pins are also cut off.
 4. The orthopedic device of claim 3, further comprising a distal cutting block mounted on a pair of anterior alignment pins from the plurality of alignment pins.
 5. An orthopedic device comprising: a patient-specific femoral alignment guide operable for preparing a distal femur of a patient for a resection during joint arthroplasty, the femoral alignment guide including a patient-specific engagement surface configured to be complementary to an anterior-distal surface of the distal femur, the femoral alignment guide including first and second anterior guiding formations defining first and second anterior guide bores and first and second distal guiding formations defining first and second distal guide bores; a plurality of cannulated alignment pins including anterior and distal alignment pins receivable through the anterior and distal guide bores for attaching the femoral alignment guide to the distal femur, wherein the alignment pins are resorbable and configured to be cut off from the distal femur; and a cutting block including a plurality of pins configured to be received into corresponding cut-off distal alignment pins. 